Sulfate Reducing Bacteria (SRB) and its associated bacteria are present in industrial waters, SRB produce hydrogen sulfide (H2S), which is a poisonous gas that can kill living beings. These bacteria produce high rates of material corrosion, which eventually cause materials destruction. In the case of oil production fields, when high concentrations of H2S are generated, destruction occurs by corrosion of injection pipe equipment and wells. Causing often the abandonment of oil fields because the danger operation under these conditions, thus losing valuable oil reserves.
In addition to economic damage resulting from the loss of equipment and non-exploitation of oil reserves, production of H2S causes high pollution of the environment and can affect the health and even the life of living beings, whether human, animal or plants.
The Greather amount of H2S is formed in the biofilm. Biofilm protects the bacteria from the action of biocides. Most biocides wear out breaking the biofilm and when the biocide reach the bacteria, biocide do not have enough power, or the concentration required to kill bacteria is low and under these conditions the bacteria develop resistance to biocides.
The harmful effects of SRB, their associates and the biofilm they form have been addressed in several technical documents. Some existing patents and articles related with the treatment of contaminated fluids using Electro Magnetic Fields (EMF) are mentioned in the next paragraphs.
The paper “Effect of electric fields for reducing membrane fouling in dead-end filtration”, Desalination and Water Treatment, Young G. Park, 2011, is related with the purification of the cell suspension in the process of the membrane under the influence of an electric field. This document shows an example of membrane process; the filtration time is reduced by the use of an electric field. However, the difference with the present invention is that it does not describe the arrangement or apparatus for generating the EMF and the document is oriented electro-hydraulic filtration processes.
The paper “Membrane cleaning using electric pulse in dead end ultrafiltration of proteinaceous solution”, ASEAN Journal on Science and Technology for Development, A. L. Ahmad, 2001, refers to ultrafiltration through membranes and proposes a method for preventing the continuous formation of proteinaceous solutes on the surface of the membrane using electric pulses under the following conditions:                1. Variation of applying pulse interval        2. Variation of the pulse duration        3. Variation of the feed pH        4. Variation of ionic electrolyte effort        5. Variation of feed concentration        6. Variation of the electric field strength (voltage)        7. Using a computer and software to collect data, control and operational parameter setting        8. Application of 100V with 10 seconds pulse duration for each pulse interval of 10 minutes. Pulses of 100 V with 3, 5, 7.5, 10, 15, 20 and 40 duration seconds were also applied with pulse intervals of 20 minutes.        
The findings reported herein suggest that the magnitude of the electrophoretic force is the main cause to kill bacteria under the influence of an electric field (pulse) having a linear relationship with the applied voltage. However, the difference with the present invention is that in the method of Ahmad, voltages between 12.5 V and 100 V are used, as in this invention the used voltages are between 0.1 V and 12 V. Additionally, this article does not describe the arrangement or apparatus by which EMF are generated.
The U.S. Pat. No. 7,033,481, patent “Electroionic processing system”, presents an electro-ionic treatment that uses Alternate Current (AC) of high frequency to treat potable water, process water, residual water, bio-solids, muds as primary and secondary effluent and other biochemical process functions. In this patent the EMF are generated and coupled to an electrolytic apparatus through an apparatus a direct method, an apparatus and method of capacitive coupling and apparatus and method of inductive coupling.
The differences mainly refers to that the present invention handles low voltages and low frequencies, while the patent in question uses a current up to 150 kA (3 kV and 0.02Ω resistance) and uses frequencies between 20 kHz to 400 kHz. Additionally, in the arrangement for generating EMF electronic components such as capacitors and inductors are used, these elements are not part of the present invention.
U.S. Pat. No. 8,920,647, entitled Apparatus for preventing scale deposits and removing contaminants from fluid columns (which is a continuation in part of U.S. Pat. No. 8,066,886, also analyzed herein), describes a method and apparatus that provides a pulsating treatment to a fluid in a plurality of different points using pulsating magnetic energy concentrated at a plurality of different areas along the flow path of the fluid. Contrary to this patent, in the present invention is described in more detail the action of EMF into the cell, not coil conductors are used to generate EMF and a special arrangement is used for electrical connection, where the electrical conductor is not wounded around the pipe forming a coil. Additionally, a software (computer program) that controls EMF generation is used.
Furthermore, in US patent electrodes can be energized with electrical power, having an AC component or DC component. When the electrodes with electric power having a Direct Current (DC) component are energized, the polarity of the signal applied to the electrodes can be reversed periodically to reduce the presence of contaminants on the surfaces of the electrodes. The power supply can establish a pulse output having an AC component through a switching sequence. This makes the inventive concept quite different from that is handled in the present patent application.
Another patent application which concerns the issue is U.S. Pat. No. 3,753,886, entitled “A Selective destruction of bacteria,” which describes a method and means for water purification and water based liquids, where a controlled amount of electrical current AC passes through the liquid to destroy all life forms in it and in this way to purify it. For this purpose a metal hollow element (tube) having an elongated terminal electrically connected to a source of electrical energy is used. The element is grounded and covered by an insulating material. The liquid in the element acts as a conductor between the terminal and grounded element, causing electric current to flow through, causing the liquid to be purified. In the patent application an alternating electric current of approximately 60 cps (Hz), from 2 to 8 amps, a voltage between 7 and 28 V is passing through the fluid to destroy impurities by vibration. This current is passed through the liquid from 1 to 8 minutes, until the liquid reaches a desired level of purity.
The main differences between the cited patent and the present invention is that the treatment process of fluids with EMF can be made continuous and/or pulsating manner and the control of the generation and application of EMF's is via a software developed for this purpose. The fluid treatment can be made in line (continuously in time) with other process in a plant.
Another important point is that differential values of the voltages used herein are between 0.1 and 12 V, which is lower than the values applied in the patent, which are between 7 V and 28 V. Added to the above, in the patent a metal hollow element (tube) having an elongated terminal electrically connected to a source of electrical energy is used. This element is grounded and covered by an insulating material.
Unlike the proposal, in the present invention the insulated conductor that goes inside the pipe is not landed, it is connected to an AC power source. Furthermore, the pipe arrangements in which the electric and magnetic fields are applied preferably are cells curved in “U” forms, electrically isolated from each other, and sections formed by groups of pipe cells.
The U.S. Pat. No. 4,572,775, whose title is “A Apparatus for sterilizing fluids” describes a method and apparatus which uses electrical current to remove bacteria from liquids. This method consists of a combination of two coils of electric conductive material, having a power input with a flow direction, so that an intense electric field is created through the liquid containing bacteria.
The main differences with the present invention are that the apparatus here disclosed uses alternating current while the patent in question employs direct current. Also, the U.S. Pat. No. 4,572,775 patent states that the electric current flows through the fluid. The process includes a preliminary step filtration of large particles, and the apparatus comprises helical coils and its respective nucleus.
U.S. Pat. No. 8,273,251 describes a process using a feed stream fluid that flows, subject to electromagnetic pulses, and a filter element through a feed pipe inlet for the filter element. As read in this document a coil assembly is disposed in the feed inlet duct and connects a power source of AC coil assembly. Unlike the present invention, this patent relates to a system of cross-flow filtration, having a coil assembly includes switches with which the current pulses are produced and focus especially in solid-state switches (SCR Silicon-Controlled Rectifier).
U.S. Pat. No. 7,887,708, entitled “Method and device for water treatment using an electromagnetic field”, describes a method comprising the steps of subjecting the water to an electromagnetic field generated by an inductive coil and varying the frequency of an excitation signal for the inductor coil, such that the electromagnetic field generated has a variable frequency.
The main differences of the present invention with the referenced patent are that in this patent varies the frequency used between 100 kHz and 500 kHz and an induction coil with a controller unit is required, this unit requires a programmable integrated circuit. The frequency range recommended to prevent algae growth with the method proposed U.S. Pat. No. 7,887,708 is between 5 kHz and 30 kHz and the range of the required current between 0.1 amperes and 10 amperes, while the frequency range preferred for water disinfection and removing bacteria is between 5 kHz and 500 kHz and the range of the required current is greater than 500 milliamps.
Analysis of the state of the art also includes U.S. Pat. No. 7,910,006, which defines a method for electromagnetic treatment of water having biological activity. The basis of this document is the principle that in the absence of an electric field, a balance exists between the hydroxyl ions and hydronium ions. If an electromagnetic field that polarizes water is applied, these two ions move independently and the equilibrium is broken. These ionic compounds may be absorbed, for example, in colloidal particles and thus a process for treating water is generated by an electromagnetic field that seeks to make the water biologically active.
The main differences of the present invention application with this patent refers to the method that is used to promote biological activity, for example, acceleration of plant growth and improve the bioavailability and efficacy of weakly diluted active ingredients, and to eliminate contamination of various types of water. In this case, a gas is used as the main element of the invention for purification of water. The frequency used is lower than 50 kHz and the power used is 1 mW/cm2.
U.S. Pat. No. 8,066,886, entitled “Method and apparatus for preventative scale deposits and removing contaminants from fluid columns”, describes a method and apparatus for treating fluid by pulses at a plurality of different points using pulsed magnetic energy concentrated in a plurality of different along a path of fluid flow areas. Provides a conduit (tube) magnetically conductive, an electrical conductor comprising at least one length of electrically conductive material having a first lead wire and a second wire conductor, a source of electrical energy, each power supply has a capacity for produce at least a different programmable output power continuously changing. It turns on and off at a frequency of pulse repetition to establish at least one output pulse of electricity. Different from the proposal of the present invention, this patent uses continuous current and alternating current patent comprises an apparatus for dispersing a chemical that is applied to fluid passing through the magnetic flux. Additionally, the arrangement of the apparatus and electrical circuits that generate the magnetic flux are completely different, from those cells and sections used as described herein.
U.S. Pat. No. 8,382,992 discloses an apparatus for disinfection of a fluid. The apparatus have a structure containing a fluid; this structure has a first cylindrical electrical conductive body oriented inwardly; a second cylindrical conductor of electricity facing outwards and disposed within the first body. These conductors facing each other in parallel and coaxial relation, and spaced to define a cavity that is filled by the fluid; and an electrical power source coupled between the first cylindrical body and the second cylindrical body. This power produces an electric field between them. This patent uses frequencies between 2 kHz and 5 kHz, the current is between 2 amps and 4 amps, employs pulses square waveform, the duct is coated with PVC and the applied voltage is 90V. While the arrangement of the apparatus of the present invention comprises cells and sections therefore is completely different from that proposed in the patent.
U.S. Pat. No. 8,784,667 is related with a method and apparatus for a plurality of treatment fluid comprising a first and a second fluid flow conductor not magnetically conductive sleeve within at least one segment of magnetically conductive conduit, It provides a plurality of different areas of concentrated magnetic energy. The present invention avoids the formation and accumulation of pollutants within the ducts and equipment used in transportation, delivering and processing fluid columns. Unlike the present invention, this patent uses direct current and alternating current and discloses an apparatus for dispersing a chemical to apply the fluid passing through the EMF. This patent is the original application, which U.S. Pat. Nos. 8,920,647 and 8,066,886 are derived. As with the latter, the arrangement of the present invention differs in that the device comprises cells and sections.
U.S. Pat. No. RE 43,332, entitled “Method and device for disinfecting and purifying liquids and gasses”, relates to a method for disinfecting and purifying liquids and gasses comprising: a) passing liquids or gases through a reactor or combination of reactors, which have a truncated concentrator compound geometry; and b) simultaneously delivering and concentrating electromagnetic and acoustic energies diversified within a predetermined and specific interior space of said compound concentrator reactor, forming a zone of high energy density in said reactor or reactors over a period of predetermined time. The main differences with the present invention is the use of ellipsoidal concentrator, the use of photocatalytic chemical substrates such as TiO2 and SiO2, and the fact that the electromagnetic energy used is ultra-violet (UV) radiation. The arrangement of the apparatus of the present invention comprises cells and sections, it is completely different.
Although several patents related to the application of electric and magnetic fields for water treatment are reported in the prior state of the art, there was a need for a simple device, inexpensive that allows to handle large volumes of fluids, online, to eliminate existing pollution in wastewater. By generating strong electric and electromagnetic magnetic fields from alternating current low-voltage and low frequency, enabling the economic viability of the industrial process and ensure the complete removal of bio-contaminants, including sulfate reducing bacteria (SRB), without adding chemicals, making additional physical treatments or consume high amounts of energy.